[amsat-bb] Re: searching advice on low hpass filter for 146 MHz

[John Geiger]

I believe DCI makes a 144-146 bandpass filter.

73s John AA5JG

----- Original Message ----- 
From: "Werner Kullmann, HB9BNK" <hb9bnk at uska.ch>
To: <amsat-bb at amsat.org>
Sent: Wednesday, April 27, 2011 1:41 PM
Subject: [amsat-bb] searching advice on low hpass filter for 146 MHz


> To improve the reception of  the sats on 145.9xx MHz with my
> little yagi, I recently acquired a SSB-preamplifier SP-2000. To my
> dismay, the reception on my IC910H was intermittend heavily
> distorted.
>
> After a while I found, that a nearby located commercial
> transmitter (POCSAG) emitting bursts on 147.300 is so strong, that
> the frontend of the IC910H (or its AGC) practically quites the
> receiver on 145.900.  When the bursts stop, reception resumes.
> Difficult to qso.
>
> I have experimented with a large cavity filter and found, that the
> impact of the bursts can be reduced, so that normal satellite work
> is possible again.
>
> Now I am looking for advice on how to build a steep low pass
> filter, eliminating everything above 146 MHz, to be mounted before
> the preamp on the mast. The filter must however be capable to
> accept the rf power, if I work in V/U mode.
>
> Thank you for any ideas !
>
> Werner, HB9BNK
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